1. Field of the invention
The present invention relates to an image data processor for generating a page raster that is image data rasterized by each page based on page description data described in page description language for variable printing, and an image data processing program storage medium storing an image data processing program that causes an information processing apparatus to operate as the image data processor.
2. Description of the Related Art
For example, there have been variable printing in which a variable object that is an image object used only once on a particular page is combined with a reusable object that is an image object used repeatedly over plural pages. One application of the variable printing is, for example, an advertisement addressed to a different individual name but contents of which is almost the same, for example, formed by picture patterns.
Generally in the variable printing, plural image objects need to be merged by each page, which is time-taking processing and thus speeding-up of the processing is desired.
Japanese Patent Application Publication No. 2005-210395 proposes a technique of speeding up RIP (rasterize) processing for generating an object raster in the variable printing. However, the proposition described in the above-identified publication employs a method of arranging objects sequentially one by one, at each position in the order specified in PPML input in the printing system, in regard to the processing of generating a page raster by merging object rasters, and does not describe any special technique in speeding up merge processing.
Therefore, in the processing method proposed in the above-identified publication, when there are plural objects that are commonly used over pages (reusable object), processing of arranging same objects at same positions by each page (merge) is generated.
Merging objects consists of processing of (1) Obtaining an object image, (2) Calculating a cut region of the object, (3) Calculating an arrangement area of a page, and (4) Merging an effective area of the object on a predetermined position of the page. Of the four processing, (1) to (3) are overhead processing. In merging images having a same area (size), productivity declines when many small objects that are cut into small pieces are arranged, by the number of times overhead processing is performed, compared to a case where a few large objects are arranged.